The present invention relates to a DC backup power supply device and more particularly, to an improvement in a DC backup power supply device including a charging/discharging circuit for performing its power charging/discharging operation between a battery and a DC path and also to a method for diagnosing the device.
In a communication or information device such as a server, router or display array device; an AC/DC converter receives a commercial AC voltage, converts the AC voltage to a desired DC voltage required by a load within the device, and supplies the DC voltage power thereto. In particular, in a device such as a communication or information device which is required to have a high reliability, for the purpose of increasing the reliability of a power supply within the device, it is general to drive the AC/DC converter in a parallel redundant manner. In order to increase a reliability to the commercial AC power input, further, such a means is also employed as to receive a two-channel AC power as the input of the AC/DC converter. To realize a high reliability to the commercial AC power input, furthermore, there is employed such a power supply arrangement that an uninterruptible power supply (abbreviated to UPS, hereinafter) is connected between the device and the commercial AC voltage.
A DC backup power supply for supplying a DC power to a load from an AC power source via AC/DC and DC/DC converters is known as disclosed in JP-A-2000-197347. In this Publication, it is proposed to increase a conversion efficiency and reduce its volume and cost by connecting an intermediate DC path between the converters to a DC backup power supply.
The above related technique had a problem that no consideration is paid to an abnormality in parts within the DC backup power supply, resulting in a lack of reliability.